The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Typically, engine water pumps are belt-driven centrifugal pumps that circulate coolant through an engine to cool the engine. Coolant is received through an inlet located near the center of a pump, and an impeller in the pump forces the coolant to the outside of the pump. Coolant is received from a radiator, and coolant exiting the pump flows through an engine block and a cylinder head before returning to the radiator.
In conventional water pumps, the impeller is always engaged with a belt-driven pulley. Thus, the pump circulates coolant through the engine whenever the engine is running. In contrast, switchable water pumps include a clutch that engages and disengages the impeller to switch the pumps on and off, respectively. When an engine is initially started, the pumps may be switched off to reduce the time required to warm up the engine and to improve fuel economy. However, the impeller may not disengage as commanded due to, for example, a clutch stuck in an engaged position.